ESD Anti-Static Bags – A Guide to Materials and Applications

There are many options when it comes to flexible ESD safe packaging materials.  Choosing the right material for the right application can be confusing.  For example, do I need a static shielding bag or a pink antistatic bag to ship my product?

Static Shielding Bags
Transparent static shielding bags are constructed of multiple layers of aluminum shielding, polyester and static dissipative polyethylene and typically printed with an ESD warning symbol.  Shielding bags are used for the storage and transport of electronic devices that are susceptible to static discharge.  Shielding bags provide Faraday Cage protection for ShieldingBagelectronic devices.  A Faraday Cage creates a protective barrier from electrostatic charges protecting items inside the bag from harmful static charges.  Similar to a conductive tote box with a lid, a shielding bag creates a protective enclosure that “shields” items from harmful static charges.  There are two types of static shielding bags available, metal-in construction (buried layer) and metal-out construction.  The most commonly used shielding bag is metal-in construction; provides excellent ESD protection and is cost effective.  Metal-out bags have a lower resistance reading due to the metal layer being closer to the outside of the surface – used in critical electronics applications and disk drive manufacturing.  Metalized shielding film can be converted into flat bags, ziplock bags, tubing and roll stock sheeting.

Antistatic Poly Bags
Antistatic poly bags provide basic low end ESD protection at the most economical cost.  Humidity independent and amine free, antistatic bags are constructed of polyethylene plastic.  Unlike shielding bags, antistatic bags do not provide Faraday Cage protection – a static charge can enter the bag! Antistatic poly bags may be used for products that do not require 985_xlFaraday Cage protection, but are used in an ESD safe environment.  For example, you may be shipping cables or bolts that are not ESD sensitive parts, however your customer will be opening them in and around ESD sensitive items in a static safe work environment.  Antistatic poly bags may also be used when storing or handling ESD sensitive items in an ESD safe work area.  If an ESD sensitive device is taken outside of an ESD safe environment, it should be placed in a shielding bag or conductive container.  Antistatic bags are available in a wide variety of thicknesses from 2-8 mil – 6 mil material meets the electrical requirements of MIL-PRF 81705D Type II.  Available in pink, blue and clear, open top or ziplock, tubing and roll stock sheeting.

ESD Moisture Barrier Bags
ESD moisture barrier bags (Dri-Shield Bags) are designed for vacuum sealing applications and provide protection against moisture, corrosion, electrostatic discharge, EMI and physical damage.  Featuring a low moisture vapor transmission rate (MVTR) Dri-Shield bags are constructed Barrier_Bag_Dri-Shield_3000of multiple layers of metalized polyester.  Thicker than standard shielding bags, moisture barrier bags provide excellent puncture resistance.  When selecting a moisture barrier bag, it’s important to know your shipping or storage cycle.  Select a bag with a MVTR to meet your needs, as well as thickness that will provide puncture resistance when vacuum sealing.  The most commonly used Dri Shield material is the 3.6 mil thickness – Dri Shield 2000.  For stricter applications or for more puncture resistance, films are available up to 7 mil in thickness. For military specification applications, choose CADPAK ESD film, meeting MIL-PRF-81705D Type I Class I. Printed with the mil-spec on the bag, this film meets the requirements as they appear on the Navy Qualified Products List (QPL) for low MVTR and maximum physical strength.

Conductive Bags
Black conductive bags provide Faraday cage protection and are constructed of conductive carbon loaded polyethylene.  Easily grounded, conductive CP14BlackConductivebags are not affected by age or humidity and do not slough.  The standard thickness is 4 mils and offers good reusability due to their flexibility and no metal layers to break down when wrinkled.  Excellent choice for packaging electronics, chemicals and powder explosives when clean, permanent ESD protection is required.  Available in flat and ziplock bags, tubing and roll stock sheeting.

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